1. Field of the Invention
The present invention relates to a method for fabricating an interlayer, and particularly relates to a method for fabricating an interlayer PCBM which is difficult to be dissolved in organic solvents.
2. Description of Related Art
In the process of manufacturing photoelectric devices (such as solar cell), donors are mixed with acceptors for increasing contact area between the donors and the acceptors. Although the contact area between the donors and the acceptors is increased by this way, the donors and the acceptors cannot be arranged in a predetermined or desired direction. This is because the distribution of the donors and the acceptors is random when the film made of the donors and the acceptors is formed. Therefore, many methods are developed to solve this problem and to make the acceptors be arranged in a predetermined or desired direction when the film made of the donors and the acceptors is formed. Addition of an interlayer PCBM is the simplest way to solve this problem.
However, there is a serious drawback in the method of addition of an interlayer PCBM. The interlayer PCBM is easy to be dissolved in an organic solvent. The mixed solution of the donors and the acceptors, which is used to coat on the interlayer PCBM, is prepared in an organic solvent, too. Therefore, when the mixed solution of the donors and the acceptors is coated on the interlayer PCBM, the interlayer PCBM will be dissolved in the mixed solution of the donors and the acceptors and removed by this mixed solution. Thus the thickness of the interlayer PCBM cannot be controlled, and the distribution of the donors and the acceptors and the quality of the film made of the donors and the acceptors cannot be efficiently controlled. Furthermore, the quality of each photoelectric device cannot be controlled because of this drawback, and it results in low yield rate.
Therefore, there is a need for a method for fabricating an interlayer PCBM which is difficult to be dissolved by organic solvents. The method can efficiently control the thickness of interlayer PCBM, and further, the method can efficiently control the distribution of the donors and the acceptors and the quality of the film made of the donors and the acceptors. Therefore, the yield rate of photoelectric devices can be improved.